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Emergency Spillwa <br />The emergency spillway must be placed between the maximum water surface <br />elevation of 6449 and the upper limit of the 1Q-year event runoff storage <br />volumes 6447.8. The following calculations demonstrate that the inlet <br />weir and 36-inch pipe spillway have sufficient capacity. <br />At entry weir do <br />Length of weir <br />` required Q = <br />32 c <br />L = <br />q = <br />dc= <br />0.314 v 9` <br />CLH1'S H is restricted to 1.5 feet <br />Fs = 3.0 x L x 1.51'5 <br />5.81' use 6 feet <br />32 cfs / 6 ft = 5.33 cfs/ft <br />0.314 5.332 = 0.96 feet <br />Determine normal Total energy over weir = 1.5 do = 1.44 ft <br />depth <br />This corresponds to elevation 6449.24 <br />_ see sketc}. , next pages <br />~~ .. <br />Assume no losses thru contraction, at 2 feet <br />from weir, b = 4.375 ft. <br />Assume dn, calculate v2/2g, total E, check with <br />value at the weir <br />Calculation of flow profile through transition <br />L d~ b A v v2/29 i E F= v/~ <br />2 l.0 4.375 4.375 7.31 0.83 47.3 49.13 1.51 <br />3 1.1 3.563 3.919 8.16, 1.04 47.05 49.19 1.37 <br />4 1.4 2.75 3.85 8.31 1.07 46.80 49.27 oK 1.z3 <br />Therefore, depth of flow is 1.4 feet at pipe entrance <br />Find required slope for 36-inch CMP <br />Z=Q/~g=5.66 <br />Z/do.5 = 5.66/32.5 = 0.363 <br />from Chow Fig. 4.1 y/do = 0.61 yc = 1.44 (.61) = 1.83 ft <br />1.411.83 = 77~ of dc, OK <br />d/D = 1.4/3.0 = 0.47 <br />from Chow, Fig. 6.1 AR2/3/ d8/3 = 0.105 <br />32 x 0.25 2 <br />S - 0-075 <br />1.486 x 38/3 x 0.105 <br />n <br />24C <br />